1. Field of the Invention
This invention relates generally to a DC-AC inverter, and more particularly is directed to an improved self-excited DC-AC inverter which is especially suited for inclusion in a DC-DC converter.
2. Description of the Prior Art
DC-DC converters have been provided for converting one DC voltage to another DC voltage. Generally, such DC-DC converters include a switching circuit actuated by a control arrangement for converting a DC voltage to an AC voltage, and a rectifier for converting the AC voltage generated by the switching circuit into the desired DC output voltage. As the control arrangement for the switching circuit, an existing DC-DC converter includes an oscillation transformer having a core with windings thereon from which pulses are applied to the switching circuit for controlling the latter in response to an AC voltage and AC current derived from the switching circuit and which are fed back to feedback windings of the oscillation transformer so as to maintain the desired oscillation. In a DC-DC converter of the foregoing type, the efficiency is determined by the permeability of the oscillation transformer core. Therefore, in order to attain high efficiency, a core material of high permeability is required. However, in general, a core material of high permeability has a low Curie temperature. When the temperature of the oscillation transformer increases during use, the oscillation frequency becomes unstable if the transformer has a core with a relatively low Curie temperature. Therefore, it has been very difficult to provide a DC-DC converter which includes a DC-AC inverter of high efficiency and with a stable oscillating frequency.